The Mechanical Handling and Storing of Material

$6o THE MECHANICAL HANDLING OF MATERIAL 1 he flaming is constructed of steel plates and angles, braced vertically and horizon- tally, and secured to the concrete foundations by eight wrought-iron bolts and nuts. The hoist-cradle is similarly constructed. The floor is timbered on each side of the rails. The tipping frame, which is also of steel, is hinged at the front end of the cradle, and is fitted with rails having turned-up ends, while to the rear is a cross-beam, to which the tipping ropes can be attached. The two hoisting ropes are 7| in. in circumference, and have a bi caking strength of about 195 tons. I he tipping ropes are of 4^ in. circumference, with a breaking strength of 72 tons. The cradle guides are formed of steel angle-bars bolted to timbers, which are carried on the sides of the framing. On the under side of the frame is a hopper, built up of steel plates and angles, for dealing with hopper wagons, an automatic tumbling apron being fitted to bridge over the space between the lower edge of the hopper and the heel end of the main shoot. The lifting machinery consists of three hydraulic cylinders bolted to steel girders, and secured vertically to the side of the framing. The plungers in the cylinders are of cast iron, and work downward through a gland acting on the cross-head. This is fitted with guides, one on each side, working on wrought-iron guide bars, each of which is cairied at three points by brackets fixed on the girders on the hoist cradle. The cross-head is fitted with sheaves for taking the tipping ropes, as well as the multiplying sheaves for the lifting ropes, the ratio being 2 to 1. Conveyance sheaves are also fitted on the frame. One of the cylinders is arranged to be in constant communication with the accumulator, so as partially to balance the weight of the cradle and minimise the amount of pressure water used. When the maximum load of 30 tons is being lifted, all three cylinders are in use ; but for raising 20 tons two cylinders suffice. The hydraulic cylinder for tipping the cradle is placed over the lifting cylinders. 1 he multiplying sheaves fitted in this case are in the ratio of 2 to 1. The arrangement of the lifting and tipping ropes is such that the tipping-frame can be tipped at any point of the vertical range of the cradle. The shoot, which is of steel plates and angles, is fitted with hinged doors at the nose end, adjustable by chains to regulate the flow of coal. The outer end is raised or lowered by steel wire ropes, each 4^ in. in circumference, and having a breaking strain of 80 tons. 1 he shoot projects 25 ft. from the face of the framing when at the usual angle foi working. I he maximum height of the under side of the nose end is •56 ft. foi fixe of the hoists and 42 ft. for one hoist above the quay level when the shoot is at the usual angle for shipping coal. A lengthening piece (6 ft. long) for the shoot is arranged for, and slides on the shoot, being adjustable through a worm and a rack by hand gear on the cradle. The working valves for the lifting and tipping machinery are of the balanced mitre tjpe, having cast-iron casings with gun-metal spindles and seats. The valves are placed at the bottom of the framing, and are operated from the working cabin placed on the framing of the hoist. 'I he valves in connection with the hydraulic engine for operating the shoot are located in the same place. There is also, adjustable from the working cabin, the automatic cut-off gear fitted on the lifting motion to bring the cradle to rest at any predetermined height. Stops are fitted on the rail level at the entrance to the hoist, and these are actuated automatically through levers and counterweights by the rise and fall of the cradle, the arrangement being such that the stops come into action, and prevent the wagons running into the hopper well when the cradle is raised. I he hoisting and tipping machinery is, of course, encased in corrugated steel sheeting, fixed on steel frames.